diff options
Diffstat (limited to 'drivers/mtd/spi-nor/otp.c')
| -rw-r--r-- | drivers/mtd/spi-nor/otp.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c new file mode 100644 index 000000000000..075b7290a95d --- /dev/null +++ b/drivers/mtd/spi-nor/otp.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * OTP support for SPI NOR flashes + * + * Copyright (C) 2021 Michael Walle <michael@walle.cc> + */ + +#include <linux/log2.h> +#include <linux/mtd/mtd.h> +#include <linux/mtd/spi-nor.h> + +#include "core.h" + +#define spi_nor_otp_region_len(nor) ((nor)->params->otp.org->len) +#define spi_nor_otp_n_regions(nor) ((nor)->params->otp.org->n_regions) + +static loff_t spi_nor_otp_region_start(const struct spi_nor *nor, unsigned int region) +{ + const struct spi_nor_otp_organization *org = nor->params->otp.org; + + return org->base + region * org->offset; +} + +static size_t spi_nor_otp_size(struct spi_nor *nor) +{ + return spi_nor_otp_n_regions(nor) * spi_nor_otp_region_len(nor); +} + +/* Translate the file offsets from and to OTP regions. */ +static loff_t spi_nor_otp_region_to_offset(struct spi_nor *nor, unsigned int region) +{ + return region * spi_nor_otp_region_len(nor); +} + +static unsigned int spi_nor_otp_offset_to_region(struct spi_nor *nor, loff_t ofs) +{ + return div64_u64(ofs, spi_nor_otp_region_len(nor)); +} + +static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len, + size_t *retlen, struct otp_info *buf) +{ + struct spi_nor *nor = mtd_to_spi_nor(mtd); + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; + unsigned int n_regions = spi_nor_otp_n_regions(nor); + unsigned int i; + int ret, locked; + + if (len < n_regions * sizeof(*buf)) + return -ENOSPC; + + ret = spi_nor_lock_and_prep(nor); + if (ret) + return ret; + + for (i = 0; i < n_regions; i++) { + buf->start = spi_nor_otp_region_to_offset(nor, i); + buf->length = spi_nor_otp_region_len(nor); + + locked = ops->is_locked(nor, i); + if (locked < 0) { + ret = locked; + goto out; + } + + buf->locked = !!locked; + buf++; + } + + *retlen = n_regions * sizeof(*buf); + +out: + spi_nor_unlock_and_unprep(nor); + + return ret; +} + +static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, + size_t total_len, size_t *retlen, + u8 *buf, bool is_write) +{ + struct spi_nor *nor = mtd_to_spi_nor(mtd); + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; + const size_t rlen = spi_nor_otp_region_len(nor); + loff_t rstart, rofs; + unsigned int region; + size_t len; + int ret; + + if (ofs < 0 || ofs >= spi_nor_otp_size(nor)) + return 0; + + ret = spi_nor_lock_and_prep(nor); + if (ret) + return ret; + + /* don't access beyond the end */ + total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); + + *retlen = 0; + while (total_len) { + /* + * The OTP regions are mapped into a contiguous area starting + * at 0 as expected by the MTD layer. This will map the MTD + * file offsets to the address of an OTP region as used in the + * actual SPI commands. + */ + region = spi_nor_otp_offset_to_region(nor, ofs); + rstart = spi_nor_otp_region_start(nor, region); + + /* + * The size of a OTP region is expected to be a power of two, + * thus we can just mask the lower bits and get the offset into + * a region. + */ + rofs = ofs & (rlen - 1); + + /* don't access beyond one OTP region */ + len = min_t(size_t, total_len, rlen - rofs); + + if (is_write) + ret = ops->write(nor, rstart + rofs, len, buf); + else + ret = ops->read(nor, rstart + rofs, len, buf); + if (ret == 0) + ret = -EIO; + if (ret < 0) + goto out; + + *retlen += ret; + ofs += ret; + buf += ret; + total_len -= ret; + } + ret = 0; + +out: + spi_nor_unlock_and_unprep(nor); + return ret; +} + +static int spi_nor_mtd_otp_read(struct mtd_info *mtd, loff_t from, size_t len, + size_t *retlen, u8 *buf) +{ + return spi_nor_mtd_otp_read_write(mtd, from, len, retlen, buf, false); +} + +static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len, + size_t *retlen, u8 *buf) +{ + return spi_nor_mtd_otp_read_write(mtd, to, len, retlen, buf, true); +} + +static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len) +{ + struct spi_nor *nor = mtd_to_spi_nor(mtd); + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; + const size_t rlen = spi_nor_otp_region_len(nor); + unsigned int region; + int ret; + + if (from < 0 || (from + len) > spi_nor_otp_size(nor)) + return -EINVAL; + + /* the user has to explicitly ask for whole regions */ + if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen)) + return -EINVAL; + + ret = spi_nor_lock_and_prep(nor); + if (ret) + return ret; + + while (len) { + region = spi_nor_otp_offset_to_region(nor, from); + ret = ops->lock(nor, region); + if (ret) + goto out; + + len -= rlen; + from += rlen; + } + +out: + spi_nor_unlock_and_unprep(nor); + + return ret; +} + +void spi_nor_otp_init(struct spi_nor *nor) +{ + struct mtd_info *mtd = &nor->mtd; + + if (!nor->params->otp.ops) + return; + + if (WARN_ON(!is_power_of_2(spi_nor_otp_region_len(nor)))) + return; + + /* + * We only support user_prot callbacks (yet). + * + * Some SPI NOR flashes like Macronix ones can be ordered in two + * different variants. One with a factory locked OTP area and one where + * it is left to the user to write to it. The factory locked OTP is + * usually preprogrammed with an "electrical serial number". We don't + * support these for now. + */ + mtd->_get_user_prot_info = spi_nor_mtd_otp_info; + mtd->_read_user_prot_reg = spi_nor_mtd_otp_read; + mtd->_write_user_prot_reg = spi_nor_mtd_otp_write; + mtd->_lock_user_prot_reg = spi_nor_mtd_otp_lock; +} |